No. 8 Oklahoma State is undefeated and has passed every test to date. But the Cowboys nevertheless are seven-point underdogs heading into Saturday afternoon’s game at Iowa State.The spread might be more of an indictment on the style of football the Cowboys (6-0, 3-0 Big 12) have played more than anything else. Four of their six wins have been decided by eight or points or less, including last week’s 32-24 victory at Texas.Still, the Cyclones (4-2, 2-1), fresh off a 33-20 win at Kansas State, are starting to round into the form that caused AP voters to place them No. 7 in the preseason.”This will be a big challenge for us,” Oklahoma State coach Mike Gundy said. “Statistically, arguably, whatever comment you want to make, (this is) the best defense we have played or could potentially play based on what people say. They’ve been good for a number of years; they’re starting to come around, in my opinion.”Iowa State is giving up league lows in points per game (16.3) and yards per game (251.3). Defensive end Will McDonald has forced three fumbles and recorded 5 1/2 sacks. Fellow defensive end Eyioma Uwazurike has four sacks, and linebacker Mike Rose is the top tackler on the team, averaging 7.2 per game.And after a slow start to the season, running back Breece Hall has sprung to life with four straight 100-yard performances, including last week’s season-high 197 yards and two touchdowns.